This invention relates to microfilm readers, and more particularly to a desk top work station having the capability of projecting microfilm images on to a top surface portion of the desk top work station.
Microfilm is a commonly used form of storing documents or graphical forms of information. The microfilm can take various storage configurations. One form is commonly referred to as microfilm jackets in which individual strips of film are placed between two transparent plastic sheets having channels to accept and retain the film. A second form similar to jackets is microfiche, in which a piece of film approximately 4 inches by 6 inches has the information photographed thereon. Microfiche can also be made by a duplicating process from an original microfilm jacket. The size of the microfiche can vary, however, the concept is to place multiple images on a single card or fiche. Another form is to have a card with a rectangular cut therein holding an individual piece of film, commonly referred to as an aperture card. The information may also be retained on rolls of microfilm which are stored in cartridges or cassettes for later retrieval.
Retrieval of the information stored on the microfilm requires the use of microform display systems such as microfilm readers. Such reader apparatus is well known, and uses a variety of means for performing their functions. Present day microfiche readers commonly use a light source, which may be a high intensity lamp, optical means for condensing the light from the lamp and directing the light through the microfilm, and a second set of optics for projecting the film image onto a reading surface. Thus, the recorded image is projected in an enlarged form to be observed by the operator.
Heretofore, microfilm readers were classified into three categories. A first category is very small handheld film readers which work either with or without a projection lamp. Often the film was placed between an external light source and an eye piece with a lens, held to the viewer's eye and individual images are read through the eye piece. This proved to be a very poor way of reading complete documents as it was inconvenient to locate the particular images, and difficult to read in this manner for any length of time. A preferable means for retrieving and reading information is the "conventional" microfilm reader. These were characteristically of two types. The first employs a rear projection or "transmission" type of screen in which an image is projected on the back of the screen and the image is observed on the opposite side of the screen. The second, is the front projection or "reflection" type in which an image is projected on the screen surface (similar to a movie screen) and the reflected light image is observed.
The problem with the conventional types of microfilm readers is that they are not conducive to the typical office setting. The working desk top area of the average person is generally cluttered with file trays, papers, calendars, desk blotters, etc., leaving little area for a microfilm reader. Furthermore, the area taken by the conventional readers is substantial and normally not justified unless the person sitting at the desk is in constant need of retrieving information on microfilm.
One reason for the large size of conventional readers is that with front or rear projection microfilm readers a complete enclosure is required. Examples can be seen in U.S. Pat. Nos. 3,997,258, and 4,167,310 wherein complete hood arrangements are required with the operator looking down into the base of the hood to view the projected image in the first mentioned patent or at the screen in the second patent. Thus, an operator could not place a device such as this in the center of his desk while trying to work on the same desk surface, or while trying to converse with a person sitting just opposite the microfilm reader.
A microfilm reader which projects downward onto an inclined base is illustrated in U.S. Pat. No. 4,164,367. However, this unit still has a back and side wall which restricts the operator's free accessibility to items other then the reader and also makes it impossible for the operator to carry on a conversation with a person on the other side of the reader. Thus, it is inapplicable for the office desk top use. Also, the projection system is located at the top of the reader making it difficult to place the film in the projection system from a sitting position and obstructs the operators line of vision within the office. A further shortcoming of this unit is that it shields the work area from ambient light at all times making it difficult to work on anything other than reading images from the microfilm.
What is required is a microfilm reader having excellent image projection characteristics, ease of usage, and not take up additional desk area while serving more than the function of being a microfilm retrieval and display device.